I only know the object style name. How can I get and modify the size options?

I only know the object style name. How can I get and modify the size options?
Something simpler.
My image object style name is mypic, and I want to modify its width.
mypic.transformAttributeOptions.transformAttrWidth = 60;
I want to reassign it to 80,

Something like this:

if(transformAttributeOptions.transformAttrWidth !=80){  
transformAttributeOptions.transformAttrWidth =80;  
abc();  
}  
else{  
aaa();  
}